Add mbedtls to pico-sdk (#894)

* Add mbedtls as a submodule

Checked out on branch mbedtls-2.28

* Add mbedtls to pico-sdk

Link your code to pico_lwip_mbedtls and pico_mbedtls.
See tls_client example in pico-examples

Fixes https://github.com/raspberrypi/pico-sdk/issues/893

test/kitchen_sink/CMakeLists.txt

@@ -142,4 +142,11 @@ if (TARGET pico_cyw43_arch)
     target_include_directories(kitchen_sink_lwip_background PRIVATE
             ${CMAKE_CURRENT_LIST_DIR})
 
+    target_link_libraries(kitchen_sink_lwip_poll
+        pico_lwip_mbedtls
+        pico_mbedtls)
+    target_link_libraries(kitchen_sink_lwip_background
+        pico_lwip_mbedtls
+        pico_mbedtls)
+    suppress_mbedtls_warnings()
 endif()

test/kitchen_sink/kitchen_sink.c

@@ -82,7 +82,13 @@
 #include "hardware/structs/watchdog.h"
 #include "hardware/structs/xip_ctrl.h"
 #include "hardware/structs/xosc.h"
-        
+
+#if LIB_PICO_MBEDTLS
+#include "mbedtls/ssl.h"
+#include "lwip/altcp_tcp.h"
+#include "lwip/altcp_tls.h"
+#endif
+
 bi_decl(bi_block_device(
                            BINARY_INFO_MAKE_TAG('K', 'S'),
                            "foo",

test/kitchen_sink/mbedtls_config.h

@@ -0,0 +1,63 @@
+/* Workaround for some mbedtls source files using INT_MAX without including limits.h */
+#include <limits.h>
+
+#define MBEDTLS_NO_PLATFORM_ENTROPY
+#define MBEDTLS_ENTROPY_HARDWARE_ALT
+
+#define MBEDTLS_SSL_OUT_CONTENT_LEN    2048
+
+#define MBEDTLS_ALLOW_PRIVATE_ACCESS
+#define MBEDTLS_HAVE_TIME
+
+#define MBEDTLS_CIPHER_MODE_CBC
+#define MBEDTLS_ECP_DP_SECP192R1_ENABLED
+#define MBEDTLS_ECP_DP_SECP224R1_ENABLED
+#define MBEDTLS_ECP_DP_SECP256R1_ENABLED
+#define MBEDTLS_ECP_DP_SECP384R1_ENABLED
+#define MBEDTLS_ECP_DP_SECP521R1_ENABLED
+#define MBEDTLS_ECP_DP_SECP192K1_ENABLED
+#define MBEDTLS_ECP_DP_SECP224K1_ENABLED
+#define MBEDTLS_ECP_DP_SECP256K1_ENABLED
+#define MBEDTLS_ECP_DP_BP256R1_ENABLED
+#define MBEDTLS_ECP_DP_BP384R1_ENABLED
+#define MBEDTLS_ECP_DP_BP512R1_ENABLED
+#define MBEDTLS_ECP_DP_CURVE25519_ENABLED
+#define MBEDTLS_KEY_EXCHANGE_RSA_ENABLED
+#define MBEDTLS_PKCS1_V15
+#define MBEDTLS_SHA256_SMALLER
+#define MBEDTLS_SSL_SERVER_NAME_INDICATION
+#define MBEDTLS_AES_C
+#define MBEDTLS_ASN1_PARSE_C
+#define MBEDTLS_BIGNUM_C
+#define MBEDTLS_CIPHER_C
+#define MBEDTLS_CTR_DRBG_C
+#define MBEDTLS_ENTROPY_C
+#define MBEDTLS_ERROR_C
+#define MBEDTLS_MD_C
+#define MBEDTLS_MD5_C
+#define MBEDTLS_OID_C
+#define MBEDTLS_PKCS5_C
+#define MBEDTLS_PK_C
+#define MBEDTLS_PK_PARSE_C
+#define MBEDTLS_PLATFORM_C
+#define MBEDTLS_RSA_C
+#define MBEDTLS_SHA1_C
+#define MBEDTLS_SHA224_C
+#define MBEDTLS_SHA256_C
+#define MBEDTLS_SHA512_C
+#define MBEDTLS_SSL_CLI_C
+#define MBEDTLS_SSL_SRV_C
+#define MBEDTLS_SSL_TLS_C
+#define MBEDTLS_X509_CRT_PARSE_C
+#define MBEDTLS_X509_USE_C
+#define MBEDTLS_AES_FEWER_TABLES
+
+/* TLS 1.2 */
+#define MBEDTLS_SSL_PROTO_TLS1_2
+#define MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED
+#define MBEDTLS_GCM_C
+#define MBEDTLS_ECDH_C
+#define MBEDTLS_ECP_C
+#define MBEDTLS_ECDSA_C
+#define MBEDTLS_ASN1_WRITE_C
+